Drill grinding appliance



Jan. 2 1937..

e. p. HARDIN DRILL GRINDING APPLIANCE Filed July 21, 1952 INVENTOR:Gardm D. Hardin,

ATTORNEYS Patented Jan. 26, 1937 PATENT OFFICE 2,068,915 DRILL GRINDINGAPPLIANCE Gordon D. Hardin, Louisville, Ky.

Application July 21, 1932, Serial No. 623,720

10 Claims.

The present invention relates to a drill grinding appliance, and moreparticularly to a device, associable with a grinding wheel, and operableto move a lip drill with relation to the grinding wheel in such a manneras to produce a drill point having a' much longer serviceable life thahas heretofore been considered possible.

A primary object of the invention is to provide an extremely inexpensivebut highly efficient tool which may be used in small shops or on the jobto grind lip drill points, and which will produce a point whichis'superior in every respect to a hand ground drill point and superiorin some respects to drill points ground on much more expensive machineswhich are now on the market. A further object of the invention is toprovide a device of the character described in which all movements ofthe drill during grinding shall be in a straight line constituting theaxis of the drill, but of such character as to produce a drill, in whichrelief is provided immediately in advance of the chisel edge, wherebythat edge is permitted to out instead of grinding during operation ofthe-drill.

A further object of the invention is to provide a mechanism of thecharacter described 1 including means for automatically advancing thedrill upon rotation thereof to produce the above mentioned relief inexactly proper proportions throughout the surface of the lands of thedrill. A further object of the invention is to provide, in a device ofthe character described, means for eifecting such advancing movement ofthe drill, such means being of such character as to be adjustable toaccommodate the mechanism to drills of varying sizes, the adjustingmechanism being graduated so that it may be readily set to the properposition for a drill of given-size by an inexperienced operator.-

A further object of the invention is to provide a device of thecharacter described which, after an initial careful positioning, may bereadily removed from its association with the grinding wheel andthereafter readily reassociated with the grinding wheel in the proper'relation thereto.

Further objects of the invention will appear as the descriptionproceeds.

To the accomplishment of the above and related objects, my invention maybe embodied in the form illustrated in the accompanying drawing,attention being called to the fact, however,

that. the drawing is illustrative only, and that change may. be made inthe specific construction illustrated and described, or in the specificsteps stated, so long as the scope of theappended claims is notviolated.

Fig.1 is a plan view of a device constructed in accordance with thepresent invention showing a drill in association with the grindingwheel;

Fig. 2 is a side elevation of such mechanism, parts being broken awayfor clarity of illustration;

Fig. 3 is a fragmentary end elevation taken from the left of Fig. 1;

Fig. 4 is a transverse section of a detail upo an enlarged scale, and

Figs. 5 and 6 are sectional views of still other details of the novelstructure.

Referring more particularly to thedrawing, it will be seen that I haveillustrated a grind- 'ing wheel HI suitably mounted upon a fixed axisll. Assuming that the grinding wheel i0 is positioned above a table orbench indicated at Si in Fig. 2, a foot piece I 2 having apertured earsI3 is positioned upon the table adjacent the grinding wheel III. Saidfoot piece is provided, in the illustrated embodiment, with a tongue I4which may, or may not, be slightly flared to form a dovetail. The footpiece 12 is so oriented with respect to the wheel I!) that the adjacentlongitudinal edge of the tongue I 4 is parallel with the outer flat faceof the grinding wheel l0; and the foot piece is fixed in this positionby lag screws, or the like, extending through the apertures of the earsII and threaded into the bench 6|. The foot piece l2, once having beenpositioned is intended to be permanently maintained in that position. g

A base member I5 is formed with-a. groove i6 adapted to mate with thetongue I4, and saidbase member is provided with a slot ll adapted toreceive a machine screw l8 which takes through said slot l1 and threadsinto a suitably provided socket in the tongue M to clamp the 40 basemember I! in adjusted position on the foot piece II. It will beperfectly obvious that, 7 once the foot piece l2 has been positionedproperly with respect to the grinding wheel III, the base member l5 maybe readily associated with said foot piece and will thereby be properlyorientedwith the grinding wheel I. In small 6 shops particularly, it ishighly desirable that' the base member and its associated elements shallbe readily removable and replaceable in its relation to the grindingwheel HI so that. said grinding wheel may be available for other workand may not be obstructed by the drill grinding appliance. The slot l1and clamping bolt 7 l8 permit adjustment of the base member IS withtated, the pin ends 4| and 4|" will ride over the cam face 46, thusreciprocating the spindle 36 to advance and retract the drill 40 withrespect to the grinding wheel Hi. Clearly, therefore, the drill 40 mustbeproperly indexed with relation to the rotative position of the spindle36 before grinding is initiated. To provide for such proper indexing, Ihave evolved the following arrangement. At a point on the spindle 36which is disposed within the hub 35, I provide a radial socket 51. Thehub 35 is formed with a radial bore 56, and the socket 51 is sopositioned that, when the pin end 4| is in the position illustrated inFig. 4, wherein it has just mounted the lower end 53 of the'cam face 46,the socket 51 is in registry with the bore 58. I prefer to provide a pin59 which, in the illustrated embodiment, is an end of a tool 60 whichforms a part of the equipment, andto enter said pin 59 through the bore58 and into the socket 51, thus locking the spindle 36 in the indicatedposition. Thereafter, a drill 40 to be ground is entered in the chuck 39and is rotated until one cutting lip of said drill is in an absolutelyhorizontal position. While a skilled operator can usually position thedrill properly by measuring the position of the critical cutting lipwith his eye alone, it is desirable for one who is not skilled in theuse of themachine to follow the following procedure. The set screw'32 isloosened and the nut 33 is rotated until the upper end of the V restlies inthe plane occupied by the center point of the drill 40. Astraight edge is then rested upon the upper ends of the wings of v,

and the drill is rotated until one of the cutting lips thereof comesinto parallelism with the lower edge of the straight edge. The chuck 39is then tightened, care being taken to prevent movement of the drill)during such tightening.

The nut 33 is now operated to elevate the V rest 34 into a positionwherein the sides of the socket lightly engage the periphery of thedrill 40, whereby said rest forms a support for the drill to preventbending thereof during the grinding operation, it being understood thatthe wheel ID will be rotated in a counter-clockwise direction as viewedin Fig. 3. ,The carriage 23 is now advanced to the position illustratedin Fig. 1, wherein the point of the drill projects just beyond theforward end of the rest 34, rough positioning of the carriage beingeffected by releasing the engagement of the member 26 with the screw 20-and final adjustment of said carriage being effected by manipulation ofthe hand wheel 2|.

It is to be noted that the base member l must be so adjusted upon thefoot member I! that, when the drill is brought fully into contact withthe flat face of the wheel ID, the spindle 36 being locked in positionby the pin 58, one cutting lip of the drill will contact the grindingwheel in a line parallel to, and spaced below the horizontal diameter ofsaid wheehthe center point of the drill being positioned very slightlybeyond the peripheral edge of said flat face. The machine hereindisclosed is so designed that the drill must engage the wheel at a pointbelow the horizontal diameter, the optimum point being dependent uponthe diameter of the wheel. However, in a machine having the range of theembodiment illustrated herein, an arrangement such that the cutting lipengages wheels from 6 to 12 inches diameter in a line spaced one inchbelow the horizontal diameter thereof will give satisfactory results ingrinding drills within the capacity of the machine. While thiscompromise position is generally satisfactory, extreme nicety may beattained by lining up the machine in such a way as to cause the drillpoint to engage the face of the wheel at a point spaced forty-fivedegrees from the horizontal diameter of the wheel; and this recommendedadjustment is independent of the diameter of the wheel.

The parts having been set up in the manner above described, the pin 59is removed from the socket 51 and the bore 58 and the spindle 36 isturned in a counter-clockwise direction as viewed in Fig. 6, whereby thepin end 4| is backed off of the cam face 46. The spring 38 thereupon, ofcourse, retracts the spindle 36 so that a slight clearance is leftbetween the drill end and the grinding wheel 18. Rotation of the wheelI0 is now initiated and,'when the wheel has obtained its normal speed,the operator grasps the hand wheel 31 and turns the spindle 36 in aclockwise direction as viewed in Fig. 6. As the spindle is turned, thepin end 4| again rides up on the end 53 of the cam face 46, thus movingthe drill into contact with the face of the wheel 10. Further rotativemovement of the spindle 36 causes further advancement of said spindleand the drill, whereby the center point of the drill is caused toproject farther beyond the peripheral edge of the wheel iii, and wherebythe followingportion of the drill land is brought into contact with thegrinding wheel. The cam face 46 is so designed that it automaticallyeffects a sufficient advancement of the drill 40 to grind the drill landin such a manner as to give an optimum relief to said land and toprovide an increasing relief adjacent the chisel point of the drill. Thepin end 4| drops off of the end 54 of the cam face 46 just as the rearedge of the drill land leaves its contact with the wheel face, wherebythe spring 38 is permitted to retract the drill 40, again providing aclearance between said drill and the wheel, and preventing grinding offof a portion of the chisel edge of the drill. The pin end 4| rides uponto the end 53 of the cam face'46 just in time to bring the second lipof the drill properly into contact with the wheel I0.

I prefer to recommend to unskilled operators that they turn the spindlethrough two complete revolutions before moving the carriage 23 from itsinitial position of adjustment in order to be certain that both lipshave been given a sufficient length of time in contact with the grindingwheel. Skilled operators, however, can obtain substantially perfectresults by giving the spindle only one revolution between advancement ofthe carriage.

After both lips of the drill have been satisfactorily ground from theinitial position of the carriage, the spindle 36 is left in a positionwherein the pin end 4| is just ready to mount the end 53 of the cam face46, and the hand wheel 21 is manipulated to advance the carriageslightly. Thereafter, the spindle 36 is again rotated, and thisprocedure is continued until a satisfactory point has been provided forthe drill.

It will be obvious that the device of the present application isextremely simple and inexpensive to manufacture; that it has fewdelicate parts which will be subject to damage or breakage, so that itcan be handled comparatively roughly with safety; and that it is capableof operation by a decidedly unskilled worker to produce excellent drillpoints. It is also obvi- InonsaidwheeLaIootmunberiimdiymsiiimcdwlihrupccttoslldwhocl,

mchtcdwithsaki!ootmunbs,almmaline mandlneansior idm.holdingmeansmbothdireetimswithrewectvidedwithacylindricalhlihadrillholder mounted in said hub forreciprocatim and rotationwithrespect thereto,andcammeamfor eilfectingreciprocation of said holder upon rotation thereof, said hub and holderbeing provided, respectively, with a bore and a socket, and said boreand socket being of corresponding diameters and beingalignedwitheachotber in one relative'position only of said hub andbolder.

4. InadeviceofthecharacterdescribeiLaba-se. a drill holder mounted onsaid base for reciprocation and rotation with respect thereto, resilientmeans tending to retract said holder, a plurality of radially oppositelyprojecting fingers carried by said holder, a cam block mounted upon saidbase and disposed in the path of movement 01 said fingers, said blockbeing oscillahle about an axis disposed substantially in the plane ofinitial contact of said fingers with said cam block, and means foreiiecting predetermined variations in' the position of said block, saidfingers and block cooperating, at times, to advance said holder againstthe tendency of said spring.

5. Ina drill grinding appliance, a member having a substantiallyhorizontal bore, a spindle reciprocably and freely rotatably mounted insaid bore, a chuck carried at one end of said spindle for receiving adrill, two fingers fixedly associated wlthsaidqhdleandloiccflngmtelyfliere- Irmflnamot-flmbeingndialwithmmectto-iddrflihdda,aeammountedad a'- cultlidsindbandpodtloncdinthepathd slidmmnsaaodatedwithsaids indleandrmmthelmeinadirectimto lxfldsfldilngersauintthetaoednidcam.mflrnlyilztheefloctmdddmckd theeoqlanfllndaidcamandm.Inadflllgflmlingamihnoaamunberlnvimaallhnfioliyhminmtalboreasindleremandfieelymtaiahlymolmtedinaid madm'ckcaniedatmemdotsudqindle'tm'mcdvingamtwofingunfimdlyaslodaind wiihnldslinllleandmoiecfingn hlymsitelyflndzmanelunmtpvoialiy' earned an nia-mhuammthemmmnnsopaalietomonemddsaid ehnmtiowardmiddmiandmansaaodatulwithnidqindleandmsilimflymgingthesam mamlnaaaunnoas saiiehnmt.

' 7.Inadrillappliance,amunbuhaving a adsiantially hmimntal bore, aqnndle Mandfledymhtahlymountedinslfl madnltmn-bdatomuniotsaidsnndle'mmavmammmnnmsfimdly nitdytherefrmanehnmt ivotallymmedonsaidmunberandposiiimedinthepathdsaid mmeansoperalfletoswmgoneenddsaidelemmt toward said chuck, said last-named meansbmngtoindicatethedegmeofstantially horizontal bore, a spindle reciprocable and freely rotatablein said bore, a chuck carried at one end of said spindle adjacent saidwheel for receivingadrilLaspringassociatedwithsaid spindle and urgingthe same away from said wheel, means limiting movement of said spindleunder the influence of said spring, two fingers fixedly associated withsaid spindle and projecting radially oppositely therefrom, a cam elementpivoted at one end adjacent said spindle and positioned in the path ofsaid fingers, and means for Swinging the free end of said element towardsaid wheel.

10. In a drill grinding appliance for associationwithagrindingwheeLamemberhavingasub-IG ing radially oppositelytherefrom, a cam element pivoted at one end adjacent said spindle andpositioned in the path of said fingers, and means for swinging the freeend of said element toward said wheel, said last-named means beinggraduated to indicate the degree of movement thereby of said element.

GORDON D. HARDIN.

